Improvement in hardening iron and steel



UNITE STATES IArE-NT OFFICE;

GEORGE J. FARMER, OF BIRMINGHAM, COUNTY OF ARXVIGK, ENGLAND.

IMPROVEMENT IN HARDENING IRON AND STEEL.

Specification forming part of Letters Patent No. H9.-36, datcd April 6, E58.

- ticularly defined, for the purpose of hardening, after they have been cut or otherwise formed, articles of iron or steelsuch, for instance, as dies for stamping, press-tools, lathechocks, files, certain kinds of cutting-tools, the

journals, bearings, and axle-boxes of running machinery, and all other similar articles or parts of machines the form, mode of manufacture, bulk, or weight of which would not prevent them from being subjected with facility to the treatment hereinafter described, and which is as follows: I take ferro-cyam'de of potassium, (the prussiate of potash of commerce,) hydrochlorate of ammonia, (the salammoniac of commerce.) and nitrate of potash, (the saltpeter of commerce,) each in equal proportions, or thereabout, reduce them to a fine powder, and thoroughly incorporate them together. I then prepare a bath by mixing the following proportions, or thereabout, of these several ingredients in cold water, namely: the prussiate of potash, two ounces; saltpeter, two ounces, and sal-ammoniac, four ounces, to every gallon of water. Having thus prepared these compounds, the first in the form of a fine powder and the second as a bath, I heat the article I am operating upon in a furnace or other fire until it has attained a red heat. I then remove it from the fire, and, if it be of a size and weight susceptible of such handling, I roll it in the dry powder, as already described, until every portion of the article shall have taken up a sufficient quantity of the mixture, or until all such portion of the article as I may require to be hardened shall be covered with the powder, which, when in contact with the heated metal, becomes immediately fused. I then plunge the article tire substance, unless the article be of considerable dimensions.

Thus far my description would apply to the treatment of such masses as could readily be turned or moved about by manual labor. For larger bodies, and such as must be raised and moved by mechanical appliances, instead of rolling them over when hot in the dry composition, which would be impracticable or difficult, I cover the mass of heated metal with the powder by employing a vessel with a perforated or colander top, from which I sift the mixture over the article under treatment, covering the surface thereof, or such portions of the surface which I may require to harden, with a thin coating of the powder, after which the immersion in the bath is to follow, as already particularized. Should it be requisite to reconvert any article thus hardened for the purpose of sharpening, facing up, or for any other operation which in its hardened state it will not admit of, this operation can be read ily effected by subjecting the article to heat under a tolerably strong blast, after which it can be cut or faced at pleasure, and subsequently rehardened to fit it for use.

I would remark that I am well aware that a process has long been known of hardening iron and steel while in course of manufacture by the introduction of the ferro-cyanide of potassium (the prussiate of potash) into a molten mass of metal, or, as it is generally termed, physicking the metal; but as this, of course,

renders the formation of tools or other articles from such metal more laborious and costly, it is utterly inapplicable to effect the result which is attained'by my invention. I am also aware that the same agent-namely, the prussiate of potashhasbeen long employed for case-hardening the surfaces of rolls to give them asteely face, but used alone and without the other ingredients I have named. By my process the metal will be indurated to a considerable depth, and I am consequently enabled to mold or otherwise shape an article into the desired form while the metal is tractable and easy of manipulation. Many things may therefore bemanufactured in cast-ironsuch as dies or other press or stamping tools, files, rasps,lathechocks, and such like articles-and I am enabled to cut, plane, or finish them in any way I please while in the soft state; and after bev ing subjected to the process herein described they will present all the appearance of caststeel, will be equally hard and durable, present as fine a surface, and for most practical purposes will prove as useful, while a considerable economy in cost of manufacture will be effected.

Having thus described the nature of my said invention, and in what manner the same is to be practically carried into effect, I Wish it to be understood that I do not confine myself to these precise details, nor to the exact proportions of the several chemical compounds herein stated, as I have merely specified those details and proportions which I have hitherto found the best suited to effect the intended purpose, and they may probably admit of some slight variation when operating upon differ ent qualities of metal.

What I claim, and desire to have secured to GEORGE JAMES FARMER.

Witnesses:

EDWARD JOHN PAYNE, I

Patent Agent, Birmingham. I. M. G. UNDERHILL,

0. A. United States of America. 

